Water and aqueous solutions as well as solutions containing water which form a foam when sprayed or heated have long been used to extinguish fire. Likewise, solutions containing water have been used for impregnation which contain, for example, inorganic salts such as ammonium salts, phosphates or water glass.
It was surprisingly discovered that citric acid salts of a specific composition for the two purposes exhibit an extraordinary fire-extinguishing and combustion-retarding action.